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linux/include/asm-generic
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Will Deacon 0bce9c46bf mutex: Place lock in contended state after fastpath_lock failure 
ARM recently moved to asm-generic/mutex-xchg.h for its mutex
implementation after the previous implementation was found to be missing
some crucial memory barriers. However, this has revealed some problems
running hackbench on SMP platforms due to the way in which the
MUTEX_SPIN_ON_OWNER code operates.

The symptoms are that a bunch of hackbench tasks are left waiting on an
unlocked mutex and therefore never get woken up to claim it. This boils
down to the following sequence of events:

        Task A        Task B        Task C        Lock value
0                                                     1
1       lock()                                        0
2                     lock()                          0
3                     spin(A)                         0
4       unlock()                                      1
5                                   lock()            0
6                     cmpxchg(1,0)                    0
7                     contended()                    -1
8       lock()                                        0
9       spin(C)                                       0
10                                  unlock()          1
11      cmpxchg(1,0)                                  0
12      unlock()                                      1

At this point, the lock is unlocked, but Task B is in an uninterruptible
sleep with nobody to wake it up.

This patch fixes the problem by ensuring we put the lock into the
contended state if we fail to acquire it on the fastpath, ensuring that
any blocked waiters are woken up when the mutex is released.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@vger.kernel.org>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-6e9lrw2avczr0617fzl5vqb8@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-08-13 18:46:54 +02:00
..
bitops Add #includes needed to permit the removal of asm/system.h 2012-03-28 18:30:03 +01:00
4level-fixup.h
atomic-long.h
atomic.h Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
atomic64.h
audit_change_attr.h audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
audit_dir_write.h audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
audit_read.h audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
audit_signal.h
audit_write.h audit: support the "standard" <asm-generic/unistd.h> 2011-05-04 14:41:28 -04:00
auxvec.h
barrier.h Create asm-generic/barrier.h 2012-03-28 18:30:03 +01:00
bitops.h bitops: remove minix bitops from asm/bitops.h 2011-03-23 19:46:22 -07:00
bitsperlong.h vsprintf: further optimize decimal conversion 2012-05-31 17:49:27 -07:00
bug.h bug.h: Fix up CONFIG_BUG=n implicit function declarations. 2012-06-25 10:32:49 -07:00
bugs.h
cache.h
cacheflush.h asm-generic/cacheflush.h: flush icache when copying to user pages 2011-05-25 08:39:37 -07:00
checksum.h Add extra arch overrides to asm-generic/checksum.h 2011-11-01 07:34:21 -07:00
cmpxchg-local.h
cmpxchg.h asm-generic: add linux/types.h to cmpxchg.h 2012-04-02 14:41:27 -07:00
cputime.h Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-06 08:44:54 -08:00
current.h
delay.h asm-generic: delay.h fix udelay and ndelay for 8 bit args 2011-07-22 18:45:33 +02:00
device.h
div64.h
dma-coherent.h common: dma-mapping: add support for generic dma_mmap_* calls 2012-07-30 12:25:46 +02:00
dma-contiguous.h mm: cma: fix condition check when setting global cma area 2012-07-06 12:02:04 +02:00
dma-mapping-broken.h
dma-mapping-common.h common: dma-mapping: introduce dma_get_sgtable() function 2012-07-30 12:25:46 +02:00
dma.h
emergency-restart.h
errno-base.h
errno.h mm: make __get_user_pages return -EHWPOISON for HWPOISON page optionally 2011-03-17 13:08:27 -03:00
exec.h Split arch_align_stack() out from asm-generic/system.h 2012-03-28 18:30:03 +01:00
fb.h
fcntl.h c/r: fcntl: add F_GETOWNER_UIDS option 2012-07-30 17:25:21 -07:00
ftrace.h asm-generic headers: add ftrace.h 2011-03-17 09:19:04 +08:00
futex.h futex: Sanitize futex ops argument types 2011-03-11 12:23:31 +01:00
getorder.h bitops: Add missing parentheses to new get_order macro 2012-02-24 10:39:27 -08:00
gpio.h gpiolib: Remove 'const' from data argument of gpiochip_find() 2012-05-18 23:01:05 -06:00
hardirq.h
hw_irq.h
ide_iops.h
int-l64.h
int-ll64.h
io-64-nonatomic-hi-lo.h asm-generic: architecture independent readq/writeq for 32bit environment 2012-02-21 16:47:28 -08:00
io-64-nonatomic-lo-hi.h asm-generic: architecture independent readq/writeq for 32bit environment 2012-02-21 16:47:28 -08:00
io.h lib: use generic pci_iomap on all architectures 2012-01-10 18:04:27 -08:00
ioctl.h
ioctls.h tty: add TIOCVHANGUP to allow clean tty shutdown of all ttys 2011-02-17 14:16:30 -08:00
iomap.h [PARISC] fix compile break caused by iomap: make IOPORT/PCI mapping functions conditional 2012-02-27 09:43:30 -06:00
ipcbuf.h
irq.h
irq_regs.h core: Replace __get_cpu_var with __this_cpu_read if not used for an address. 2010-12-17 15:07:19 +01:00
irqflags.h
Kbuild KVM: Export asm-generic/kvm_para.h 2012-05-29 12:31:01 +03:00
Kbuild.asm
kdebug.h
kmap_types.h asm-generic: remove km_type definitions 2012-07-24 15:27:30 +08:00
kvm_para.h KVM: make asm-generic/kvm_para.h have an ifdef __KERNEL__ block 2012-05-21 17:47:52 +03:00
libata-portmap.h
linkage.h
local.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
local64.h atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
memory_model.h mm: fix __page_to_pfn for a const struct page argument 2011-08-17 13:00:20 -07:00
mm_hooks.h
mman-common.h coredump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR_NODUMP 2012-03-23 16:58:42 -07:00
mman.h
mmu.h
mmu_context.h
module.h
msgbuf.h
mutex-dec.h
mutex-null.h
mutex-xchg.h mutex: Place lock in contended state after fastpath_lock failure 2012-08-13 18:46:54 +02:00
mutex.h
page.h The following changes since commit 3ee72ca992 2012-01-10 17:39:40 -08:00
param.h UAPI: Rearrange definition of HZ in asm-generic/param.h 2011-12-13 09:26:45 +00:00
parport.h
pci-bridge.h PCI: work around Stratus ftServer broken PCIe hierarchy 2012-04-30 15:21:02 -06:00
pci-dma-compat.h
pci.h PCI: collapse pcibios_resource_to_bus 2012-02-23 20:19:04 -07:00
pci_iomap.h [PARISC] fix compile break caused by iomap: make IOPORT/PCI mapping functions conditional 2012-02-27 09:43:30 -06:00
percpu.h
pgalloc.h
pgtable-nopmd.h
pgtable-nopud.h
pgtable.h thp: avoid atomic64_read in pmd_read_atomic for 32bit PAE 2012-06-20 14:39:35 -07:00
poll.h epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree() 2012-02-24 11:42:50 -08:00
posix_types.h bury __kernel_nlink_t, make internal nlink_t consistent 2012-05-30 21:04:50 -04:00
ptrace.h asm-generic/ptrace.h: start a common low level ptrace helper 2011-05-26 17:12:36 -07:00
resource.h ulimit: raise default hard ulimit on number of files to 4096 2011-05-25 08:39:43 -07:00
rtc.h
rwsem.h Hexagon: Add locking types and functions 2011-11-01 07:34:20 -07:00
scatterlist.h
sections.h x86: Separate out entry text section 2011-03-08 17:22:11 +01:00
segment.h
sembuf.h
serial.h
setup.h
shmbuf.h
shmparam.h
siginfo.h Linux 3.4-rc5 2012-05-04 12:46:40 +10:00
signal-defs.h
signal.h
sizes.h ARM: 7430/1: sizes.h: move from asm-generic to <linux/sizes.h> 2012-06-28 17:14:34 +01:00
socket.h net: Add framework to allow sending packets with customized CRC. 2012-02-24 01:37:35 -08:00
sockios.h
spinlock.h
stat.h asm-generic/stat.h: support 64-bit file time_t for stat() 2010-11-01 15:31:29 -04:00
statfs.h asm-generic: Use __BITS_PER_LONG in statfs.h 2012-04-30 12:55:15 -07:00
string.h
swab.h
switch_to.h Split the switch_to() wrapper out of asm-generic/system.h 2012-03-28 18:30:03 +01:00
syscall.h asm/syscall.h: add syscall_get_arch 2012-04-14 11:13:19 +10:00
syscalls.h
termbits.h
termios-base.h
termios.h
timex.h
tlb.h mm/mmu_gather: enable tlb flush range in generic mmu_gather 2012-06-27 19:29:11 -07:00
tlbflush.h BUG: headers with BUG/BUG_ON etc. need linux/bug.h 2012-03-04 17:54:34 -05:00
topology.h
types.h consolidate umode_t declarations 2012-01-03 22:55:17 -05:00
uaccess-unaligned.h
uaccess.h fix default __strnlen_user macro 2011-10-06 19:47:12 -04:00
ucontext.h
unaligned.h
unistd.h compat: use sys_sendfile64() implementation for sendfile syscall 2012-03-27 13:36:57 -04:00
user.h asm-generic/user.h: Fix spelling in comment 2011-03-01 15:49:39 +01:00
vga.h
vmlinux.lds.h ftrace: Sort all function addresses, not just per page 2012-05-16 19:58:44 -04:00
word-at-a-time.h word-at-a-time: make the interfaces truly generic 2012-05-26 11:33:40 -07:00
xor.h sanitize <linux/prefetch.h> usage 2011-05-20 12:50:29 -07:00